Artificial hand for prostheses with bioelectrical control



July 21, 1970 Y. s. YAKOBSON ETAL 3,521,303

ARTIFICIAL HAND FOR PROSTHESES WITH BIOELECTRICAL CONTROL Filed July 12,1967 United States Patent 3,521,303 ARTIFICIAL HAND FOR PROSTHESES WITHBIOELECTRICAL CONTROL Yakov Savelievich Yakobson, 2 Neglinny pereulok 5,kv. 8; Vitaly Moiseevich Bernshtein, Ulitsa Vavilova 36, korpus 4, kv.48; and Efim Pinkhasovich Polyan, Ulitsa Morisa Toreza 26/1, kv. 469,all of Moscow, USSR.

Filed July 12, 1967, Ser. No. 652,881 Int. Cl. A61f l/06 U.S. Cl. 3-1.13 Claims ABSTRACT OF THE DISCLOSURE An artificial hand comprises alever-joint unit for the thumb having two degrees of freedom and alever-joint system for the remaining four fingers constituted byindividual levers articulated in pairs respectively driven by a pair ofrocker units in turn connected with acommon control rocker which isdriven from a drive unit. An independent drive unit operates the thumbunit in pivotal extension, whereas a further drive unit serves forturning of the thumb unit with respect to its axis.

The invention relates to upper extremity prostheses with bio-electricalcontrol; additionally, it can find application in manipulators.

Artificial hands to prostheses with bio-electrical control which are inuse heretofore are incapable of affording diverse kinds of hand gripcorresponding to the functions of a natural human hand, and said handsare not capable of performing motorial functions when manipulation withevery particular finger is involved.-

For example, there exists an artificial hand for a bioelectricallycontrolled prosthesis, wherein movements of all five fingers are in apermanent operative connection to one another. A disadvantage of saidhand resides in that it is capable of only a grip with the fingertips(finger-pinch) An object of the present invention is to eliminateaforesaid and other disadvantages.

A specific object of the present invention is to provide an artificialhand which is capable of performing diverse kinds of grip of variousshaped objects, as well as of micromotorial functions when motion ofeach individual finger is required.

Said object is accomplished by the application of individual drivesactuating the thumb and the cluster of four longer fingers, adifferential rocker mechanism, a mechanism for transferring the thumbfrom opposition to abduction, a system of elastic links or flexible tiesrunning to each finger, a device for automatic flexion of the ungualphalanx of the thumb.

According to the invention, provision is made in the artificial handproposed here and below, for individual and independently functioningcontrol lines actuating the thumb unit which is capable of motion withtwo directions of movement, and actuating the remaining four fingers,each of said control lines incorporating an independent reversibleelectric drive which is controlled by biological currents taken offtruncated muscles and is operatively associated with a lever-jointsystem imitating the phalanges of the four longer fingers, and with anindependent lever-joint unit of the thumb.

The thumb unit is preferably made as an individual articulated lever,whereas the pivotally mounted phalanges of the remaining fingers arearticulated in pairs to two pivoted rocker arms of the differentialrocker mechanism, the midpoints of said rocker arms being articulated toa common control (master) rocker.

The aforesaid independent electric drives can incorporate micromotorsprovided with self-braking screw gears, one of said micromotorsimparting motion to said master rocker of the four-finger cluster whilethe other is coupled to the lever of the thumb.

It is likewise expedient that the pivot pins of the levers which imitatethe main phalanges of the fingers, be oriented with respect to oneanother at some angle corresponding to those inherent in a natural humanhand, whereas the levers are advantageous to be connected to thedifferential rocker mechanism through a ball-andsocket joint.

The unit of the thumb can be provided with a mechanism for an additionalpassive turning of said finger with respect to an axis perpendicular tothe axis of flexionextension thereof, an automatic spring-actuatedlocking of the finger in position being also provided.

The ungual phalanx of the thumb can be made as a spring-loaded rockermovable at an interphalangeal articulated joint.

An embodiment of the present invention is described hereinbelow by wayof example with reference to the appended drawing, wherein the solefigure thereof shows a schematic functional diagram of the artificialhand of the invention.

Referring to the drawing, the artificial hand comprises a framecontaining a drive 1 actuating a four-finger cluster 2, a differentialrocker mechanism 3, a drive 4 actuating a thumb 5, a mechanism 6 forpassive abduction of the thumb, a unit 7 of passiverotation, elasticlinks 8, and an articulated joint 9 whereby the ungual phalanx of thethumb 5 is flexed.

The longer fingers 2 of the hand can be flexed at themetacarpophalangeal and proximal interphalangeal articulated jointsthereof, whereby a first grip is rendered possible. The motion of eachfinger at the aforesaid joints is operatively associated with that ofthe other fingers. A fingertip grip occurs when the thumb 5 is inopposition to the second and third ones. This being the case, the fourthand fifth fingers are forced towards the palm, whereby the process ofwriting becomes more convenient.

The differential rocker mechanism 3 makes it possible for each longerfinger 2 to be adapted for the shape of every particular object to begripped.

The pivot pins of the metacarpophalangeal joints of the longer fingers 2are arranged at certain angles corresponding in those inherent to anatural human hand, whereby the artificial hand appears more cosmetical,a strong grip of diversely shaped objects is attained, writing is mademore convenient due to shifting of the fourth and fifth fingers towardsthe center line of the palm, the frames of the fingers 2 being connectedto the rocker mechanism 3 through ball-and-socket joints 10.

To make the motion of the longer fingers 2 more regular, as well as toprovide for motion of some fingers with the other ones pressed to thepalm, use is made of the elastic links 8 which are in effect springs andare held with one of their ends to every particular finger, and with theother end, to the body of the palm, said springs generating moments offlexure increasing sequentially from the third finger to the fifth one.

The abovesaid fact makes it possible to effect micromotions either withthe second (index) finger or with the second and third fingers at atime, with the fourth and fifth fingers clenched to the palm. So thedesign of the hand proposed here and below provides for gripping of anobject with the two or three fingers, allows operating calculatingmachines or typewriters with the index finger, makes it possible forsaid finger to pull at the trigger of a pistol or electric drill, withthe other fingers firmly clenching the instrument handle.

The principal motion performed by the thumb 5 is effected in thedirection of flexion-extension with respect to an articulated joint 11located in the area corresponding to the carpometacarpal joint of ahuman hand. The fiexion-extension axis of the artificial hand isarranged similarly to that of a natural human hand when a fingertip orfist grip occurs. To effect a side grip, provision is made for a seconddegree of freedom of motion in the direction of abduction-opposition,whereby a passive rotation of the thumb 5 is allowed with respect to anaxis perpendicular to the axis of fiexion-extension of that finger, withan automatic spring-locking of the finger 5 in a few positions. The sidegrip is of importance especially when performing various everyday-lifeand Working functions such as manipulating with a file, hack saw,hammer, and the like. A possibility is also rendered for the opening ofthe hand when abducting the thumb, this being due to the two degrees offreedom thereof.

To provide, for an automatic fiexion of the ungual phalanx of the thumb5 when a clench (or fist) grip occurs, said phalanx is made as aspring-loaded rocker 12 movable at the interphalangeal joint, wherebythe grip is made firmer and the appearance of the hand more cosmetical.

To actuate all the motions of the artificial hand, use is made of DCreversible micromotors 13 with a rating of 1.5 w. each. The micromotor13 of each drive imparts rotation through gear reducers 14 and 15 tolead screws 16 and 17 which move sliders 18 and 19 of the levertransmission, said sliders being connected to the frame of thefour-finger cluster 2 and thumb 5. To reduce noise, the housing of thereducers 14 and 15 is damped, and the connection of these to the leadscrews 16 and 17 is effected through flexible telescopic joint couplings20 and 21.

The artificial hand of the invention is provided with the mechanism 7 ofpassive rotation which is essentially a ball bearing whose ball racesare made of polyamide resins. When necessary, an automaticspring-actuated locking of the hand is provided.

Due to its small thickness and elasticity the mechanism 7 can be placedover the stump. With the presence .1

of a residual pronating-supinating motility of the stump, said mechanism7 makes it possible to utilize that motib ity for rotation of the hand.

Low power rating of the drive micromotors allows the hand to be compactand light, resembling in shape that of a natural human hand. At the sametime, due to the provision of the independent drive for the first finger5 and the possibility of self-braking of the drive of the four-fingercluster 2, the force of the grip at the fingertips can amount to 7 kg.which corresponds to a maximum force applied by the fingers of a healthyman when performing most common working and everyday-life functions.

The differential rocker mechanism 3 and both said drives areaccommodated inside a common housing which is in effect the body of thepalm and Wrist.

As the systems of stepless control of the drives actuating the presentmultipurpose artificial hand, use is made of an independentbio-electrical control by virtue of signals arriving from the fourmuscles, as well as a simplified system operated by signals taken offtwo and three muscles. One of such simplified control systems is thatproviding for flexure of the thumb 5 and four-finger cluster 2 by way ofindependent delivery of individual signals from two muscles, whereasextension of all the five fingers is effected when the aforesaid signalsare delivered at the same time.

What We claim is:

1. An artificial hand for prostheses with bioelectrical control,comprising: a frame containing a lever-joint unit for the thumb havingtwo directions of movement; a lever-joint system imitating phalanges ofthe remaining four fingers connected to one another, said systemfunctioning independently of said unit for the thumb; a first drivemeans for the four-finger lever-joint system, a second drive means forsaid unit of the thumb, each of said drive means including anindependent reversible electric drive unit adapted to be controlled bybiological currents from truncated muscles, and flexible linkstranslating motion from said drive units to said lever-joint system ofthe four fingers and said thumb unit respectively, said thumb unitcomprising an individual articulated lever, said lever-joint system ofthe remaining four fingers including respective levers for eachremaining finger, said levers being articulated in pairs, a differentialrocker mechanism including two pivotable rocker arms connected torespective pairs of articulated levers and a common control rockerarticulated to said rocker arms.

2. An artificial hand as claimed in claim 1 wherein said drive units areindependent electric drives including micromotors provided withself-braking screw gears; one of said micromotors being connected to thelever of said thumb while the other micromotor is connected to saidcommon control rocker.

3. An artificial hand as claimed in claim 1 wherein said thumb unitcomprises means for an additional passive turning of said thumb unitwith respect to an axis perpendicular to the axis of extension thereof,and an automatic spring-actuated locking means for the thumb unit. I

References Cited UNITED STATES PATENTS 2,435,614 2/1948 Tureman 312.72,500,614 3/1950 Lohmann 312.7 2,568,299 9/1951 Philpott 3-12.72,847,678 8/1958 Opuszenski 312.7

FOREIGN PATENTS 446,809 2/1948 Canada.

509,230 1/1955 Italy.

163,718 1964 U.S.S.R.

RICHARD A. GAUDET, Primary Examiner R. L. FRINKS, Assistant Examiner US.Cl. X.R. 312.7

